Animal litter and process

ABSTRACT

An animal litter is prepared by de-watering rejects of a secondary fiber plant, incorporating a deodorant therein, for example, sodium bicarbonate, pelletizing, and drying. The rejects on a dry basis consist essentially of about 50 percent to about 90 percent cellulose and from about 10 percent to about 50 percent fiber making mineral filler, usually kaolin, and sodium bicarbonate is incorporated therein in the amount of between about 1 percent to about 10 percent on the dry basis. Paper broke also may be incorporated.

This is a division of application Ser. No. 672,471, filed Mar. 31, 1976,now U.S. Pat. No. 4,203,388, issued May 20, 1980.

BACKGROUND OF THE INVENTION

This invention relates to an animal litter and a process for making thesame and utilizes for this purpose a waste product from a secondaryfiber plant, which waste product is ordinarily carted to a landfill orotherwise disposed of.

PRIOR ART

In secondary fiber plants, recycled paper from offices and elsewhere isre-pulped and re-cleaned. In the cleaning process the rejects, which maybe from screen cleaning and/or from flotation type screening or both,are pooled, transferred to a sedimentation tank to effect concentrationof the solids and the concentrated solids are pumped off from the bottomof the sedimentation tank onto a vacuum filter. The resulting matcontains about 20 to about 30 percent solids consisting essentiallybetween about 50 to about 90 percent cellulose and between about 10 toabout 50 percent paper-making mineral filler depending upon the type ofpaper which is recycled. If a large percentage of slick magazine orother highly filled paper is in the recycle, the proportion of mineralfiller will be high. Thus, the precise composition of the mat will varysomewhat according to the source of the recycled paper. Heretofore, thismat has been carted off to a landfill or otherwise disposed of.

Heretofore, aninal litter has been made of some absorbent materialcontaining a suitable deodorant material. Bactericides are alsosometimes included. As illustrative of such prior art, may be cited thefollowing U.S. Pat. Nos. 2,708,418; 3,059,615; 3,425,397; 3,636,927,3,735,734; 3,747,564; 3,765,371; 3,789,797; and 3,816,577.

OBJECT OF THE INVENTION

It is an object of the invention to provide a new and improved animallitter. It is an object of the invention to provide a process for makinga new and improved animal litter. It is an object of the invention toprovide a use for discarded waste product. It is a further object of theinvention to provide an animal litter which, notwithstanding that it ismade from a heretofore discarded waste material, is competitive with thebest animal litters available. It is a further object of the inventionto avoid the disadvantages of the prior art and to obtain suchadvantages as will appear as the description proceeds.

BRIEF DESCRIPTION OF THE INVENTION

An animal litter comprising pelleted and dried rejects of a secondaryfiber plant containing a deodorizer material is prepared by de-wateringrejects of a secondary fiber plant, cutting the rejects into smallpieces, incorporating therewith a deodorant material, pelletizing anddrying.

The deodorant material, advantageously, is sodium bicarbonate which,advantageously, is present in an amount of between about 1 percent toabout 10 percent, preferably 5 percent, based on the dry weight of thelitter. The sodium bicarbonate may be partially or totally replaced byother suitable deodorants, for example, chlorophyll, sodium dihydrogenphosphate, potassium dihydrogen phosphate, potassium acid phthalate, thewater soluble constituents of cherry pits, 2-isopropoxycamphane,2(β-hydroxyethoxy)camphane, and the like. Additionally, there may beincluded bactericides such as cetylperidium chloride, cetalkoniumchloride, and the like, which function both as a bactericide and as asurfactant. Other such dual-acting bactericides are disclosed in U.S.Pat. No. 3,765,371. There may also be included antioxidants as in thatpatent and there may also be included mold inhibitors such as propionicacid and its salts, and phenols and phenolic salts such as sodiumpentachlorophenol. Pigments and dyes may also be included, mostadvantageously, in the slurry fed to the vacuum filter. For example,along with the flocculating agent added to improve the filtration.

The basic animal litter composition of the invention is prepared fromrejects of a secondary fibre plant. The solids in these rejects consistessentially of about 50 percent to about 90 percent cellulose and fromabout 10 percent to about 50 percent paper-making mineral filler whichis chiefly kaolin or china clay. These rejects are de-watered, cut intopieces, mixed with the deodorant or other additives, pelletized anddried. To give a pelleted and dried material containing, in addition tothe solids of the rejects which consist of about 50 percent to about 90percent cellulose and about 10 percent to about 50 percent mineralfiller, about 1 percent to about 10 percent deodorizing material on adry weight basis.

In a secondary fiber plant, the raw material is recycled paper such asis collected from office buildings and the like. This recycled paperranges from highly filled paper such as the slicks used in the slickmagazines to partially filled papers such as office stationery tocompletely unfilled paper such as newsprint. In order to obtain fibersfrom such heterogenous product, the waste paper must be re-pulped andcleaned to separate from the fibers the mineral fillers and dyes andpigments associated therewith. For this purpose, the re-pulped wastepaper is subjected to a series of cleaning operations which comprisesscreening, flotation and the like and the off-colored fractions and thefractions containing the mineral fillers are what constitute therejects. These rejects are pooled and concentrated in a sedimentationtank and partially de-watered on a vacuum filter. The resulting matcontains about 20 percent to 30 percent solids consisting essentially ofabout 50 percent to 90 percent cellulose and about 10 percent to 50percent mineral filler. Sometimes there may be a very small amount ofpolyethylene or like plastic as a result of some coated papers being inthe scrap but the amount is so small as to be insignificant.

This mat is then further de-watered in a suitable press, centrifuge, orthe like, to bring the water content down to between about 32 percent toabout 40 percent. Thirty-two percent water is about as low as can beobtained in a screw press. More water could be removed in a centrifugebut in accordance with this invention it is neither necessary nordesirable at this stage to remove more of the water.

If desired, the cut vacuum filter mat can be admixed with dried paperbroke which has been reduced in size by a shredder or a hammer mill suchas produced by Sprout Waldron, Bryant-Poff, and others. Up to about 50percent advantageously, at least about 10 percent, of the cut mat solidscan be replaced in this manner. Paper broke comprises the paper scrapwhich comes off of paper machines and converting operations. The paperbroke most advantageous for use in the litter of the invention is thenon-repulpable broke, e.g., that from parchment, wet strength-treatedpaper, or resin-treated paper.

A screw press is of particular advantage when dry paper broke isincorporated with the cut mat. The screw press acts, first, thoroughlyto mix the two components and then as the squeeze or press becomesgreater, to equilibrate the moisture in the mass so that the brokebecomes wet and the moisture in the press cake is uniformly distributed.

The de-watered cake is cut into small pieces. If a screw press is used,the press operation itself will extrude the pressed cake into a suitablerod or rods which can be cut or chopped into small pieces by a whirlingblade. Sodium bicarbonate or like deodorant is then incorporated intothe cut pieces and thoroughly mixed therewith and the mixture ispelleted into suitable size pellets, dried and sterilized.Advantageously, the pellets are about 1/8 inch in diameter and about 3/8inch long. The particular size, however, is not critical and the pelletsmay range from about 1/16 inch diameter to about 3/8 inch diameter andfrom about 3/16 inch length to about 1 inch length.

The pellets should be dried, to a value, say of about 5 to about 15percent moisture, which on the low side does not tend to cause glazingof the pellets with a consequent lowering of absorptivity and on thehigh side does not deleteriously reduce the amount of water that can betaken up. Also, too much moisture may result in mold formation. Thedrying, advantageously, is effected at a temperature which gives asterile product.

Suitable screw presses for the above operation are the Anderson Pressmade by Anderson-Ibec Company and the Bauer Press made by the BauerDivision of C. E. Raymond Company. Suitable pelleting machines includethe California Pellet Mill, the Sprout Waldron Pellet Mill and the DravoPellet Mill. Suitable driers, which also act as sterilizers, are RotaryDriers or Fluid Bed driers manufactured by C. E. Raymond or JeffreyManufacturing Company.

The mineral filler will ordinarily consist essentially of kaolin orchina clay but in some cases will contain titanium dioxide, calciumcarbonate, and the like.

DETAILED DESCRIPTION OF THE INVENTION EXAMPLE 1

The wet mat of secondary fiber waste from the vacuum filter in asecondary fiber plant was charged into an Anderson Screw Press andtherein de-watered to about 33 percent water. As the pressed cake wasextruded from the press it was chopped into small pieces by a whirlingblade. These pieces were mixed thoroughly with sodium bicarbonate in theproportion of 5 percent sodium bicarbonate on a dry weight basis andpelletized in a California Pellet Mill into pellets of 1/8 inch diameterand 3/8 inch long and then dried to a moisture content of 10 percent ina Jeffrey Fluid Bed drier. The resulting product contained 65 percentcellulose, 35 percent mineral filler, and 5 percent sodium bicarbonateon a dry weight basis and was found to be an excellent kitty litter inits ability to absorb moisture and odors.

EXAMPLE 2

The process of Example 1 was repeated using 50 percent wet mat ofsecondary fiber plant and 50 percent parchment broke on a dry weightbasis. The resulting product contained about 80 percent cellulose, 15percent mineral filler, and 5 percent sodium bicarbonate on a dry weightbasis.

It is to be understood that the invention is not to be limited to theexact details of operation or structure shown and described as obviousmodifications and equivalents will be apparent to one skilled in theart.

I claim:
 1. A process for making animal litter which comprises partiallyde-watering waste rejects from a secondary fiber plant to a consistencysuch that the partially de-watered waste can be formed into pellets,forming the partially de-watered waste into pellets, and then dryingsaid pellets, in which the partially de-watered waste contains fromabout 32 percent to about 40 percent water.
 2. The process of claim 1,in which the waste is de-watered in a screw press and the press-cake isextruded from the press and chopped into pieces as it is extrudedtherefrom.
 3. The process of claim 2, in which the solids of saidpress-cake consist essentially of about 50 percent to about 90 percentcellulose, about 10 percent to about 50 percent mineral filler, andabout 1 percent to about 10 percent of deodorant material.
 4. Theprocess of claim 1, in which the partial de-watering is effected byconcentrating cleaning rejects from a secondary fiber plant in asedimentation tank, further concentrating on a vacuum filter to yield amat containing between about 20 percent to about 30 percent solids, andthen de-watering said mat to a water content of between about 32 percentto about 40 percent.
 5. The process of claim 2, in which the wasterejects are partially de-watered on a vacuum belt filter to a mat which,before de-watering in the screw press, is comingled with dried paperbroke whereby, in the de-watering step in the screw press, the wasterejects and the paper broke are comingled and equilibration of moisturein the press-cake is obtained.
 6. The process of claim 5, in which thepaper broke is non-repulpable paper broke.
 7. The process of claim 6, inwhich the waste rejects consist essentially of about 50 to about 90percent cellulose and about 10 to about 50 percent mineral filler andthe broke is essentially cellulose.
 8. The process of claim 7, in whichthe rejects comprise on a dry weight basis about 10 to about 50 percentof paper broke and the balance essentially waste rejects.
 9. A processfor making animal litter comprising de-watering waste rejects from asecondary fiber plant to a mat containing between about twenty and aboutthirty percent solids, incorporating dry paper broke therein, effectingequilibration between the paper broke and the mat and furtherde-watering the equilibrated mixture to between about thirty-two andabout forty percent water, forming the resultant mixture into pellets,and drying the resulting pellets.
 10. The animal litter prepared by theprocess of claim
 1. 11. The animal litter prepared by the process ofclaim
 3. 12. The animal litter prepared by the process of claim
 5. 13.The animal litter prepared by the process of claim 9.